Stents are placed or implanted within a blood vessel for treating stenoses, strictures or aneurysms therein. They are implanted to reinforce collapsing, partially occluded, weakened, or dilated sections of a blood vessel. They have also been implanted in other bodily vessels including arteries, veins, biliary ducts, urethras, fallopian tubes, bronchial tubes, the trachea and the esophagus.
Stents are typically either self-expanding or mechanically expandable via the application of radially outward force from within the stent, as by inflation of a balloon. Hybrid stents, e.g., stents which are both self-expanding and mechanically expandable are also known.
Stents may be produced from a wide variety of materials. Typically, radiopaque materials are incorporated into stents to facilitate visualizing them as they are delivered to desired bodily locations. The radiopaque material may be provided in the form of a coating, in the form of one or more marker bands which are attached to the stent or may be incorporated into the basic structure of the stent as by blending a radiopaque metal with a structural metal. The entirety of the stent may be radiopaque or only desired portions of the stent may be radiopaque, for example, the proximal and distal ends of the stent. In the case of a bifurcated stent, it may be desirable for the region of sidebranch access to be radiopaque.
While rendering regions of a stent radiopaque facilitates imaging the stent during delivery, the radiopacity of the stent may hinder visualizing the contents of the stent subsequent to expansion of the stent. Visualizing flow of a bodily fluid through a stent may be necessary in cases where restenosis has occurred subsequent to implantation of the stent. The darkness of the radiopaque region of the stent obscures the contents of the stent from the fluoroscopic image.
There remains a need to provide novel methods of imaging stents which allow for viewing the stent under fluoroscopy but which also allow for visualizing the contents of the stent.
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Without limiting the scope of the invention, a brief summary of the claimed embodiments of the invention is set forth below. Additional details of the summarized embodiments of the invention and/or additional embodiments of the invention maybe found in the Detailed Description of the Invention below.
A brief abstract of one or more embodiments of the invention is provided as well for the purposes of complying with 37 C.F.R. 1.72.